Booking your own excurions does save money...But, the only problem is you have no guarantees that you will get back to the ship in time. Many people do their own and have no problems, but I've seen people jumping up and down at the end of the pier as the ship pulls out....so just plan on getting back in time, the ship doesn't wait for people that book their own excursions....My feeling is that the cruiseline has a relationship with the vendors that they use and if there are any problems getting back, the ship will wait for you. Hope this doesn't scare you from taking your side trips....Just my opinion after 19 cruises....